Complement System p2 (Alternative And MBL) Flashcards
What is the concentration of properdin in the serum?
5-15 ug/mL
What is the original term for the alternative pathway?
Properdin system
What is the major function of the properdin?
C3 convertase
What serum proteins are unique to the alternative pathway?
Factor b
Factor d
What are the triggering substances for the alternative pathway include?
Bacteria
Fungi
Viruses
Tumor cell lines
Some parasites
Which immunoglobulin can trigger the alternative pathway?
IgA
What is the major factor for both alternative and classical pathway?
C3
What protein in the alternative pathway is analogous to C2?
Factor B
This protein cleaves factor B that are bounded to C3b to Bb and Ba
Factor D
Cleaves additional C3 into C3a and C3b
Stabilized by properdin
C3bBb
What happens in the stabilization of the C3bBb by the properdin?
Increased half-life from 90 seconds to several minutes
Associated with the C5 convertase of the alternative pathway
C3bBb3b
What is the first part of the formation of MAC?
C5b
Is classical pathway antibody dependent or independent?
Dependent
Considered an acute phase protein because it is produced in the liver and is normally present in the serum but increases during an initial inflammatory response
MBL
Proteins that bind to carbohydrates
Lectins
This pathway provides an additional link between the innate and acquired immune response because it involves nonspecific recognition of microbial cell walls and that are distinct from those found on human cell surfaces
Lectin pathway
What is the structure of the MBL similar to?
C1q
What serine protein has a homologous activity to C1s?
MASP-2
It takes the active role of cleaving the C4 and C2 in the lectin pathway
MASP-2
a glycoprotein that inhibits activation at the first stages of both the classical and lectin pathways
C1 inhibitor / C1INH
Where does C1INH bind to inactivate C1?
Active sites of C1r and C1s
What are the 4 main regulators that inhibit the C3 convertase
C4b-binding protein (C4BP)
Complement receptor 1 (CR1)
Membrane cofactor protein (MCP)
Decay accelerating factor (DAF)
DAF works with what protein for the inactivation of C3b and C4b?
Factor I
CR1 also known as
CD35
Most efficient cofactor for Factor I mediated cleavage of C3B
Also serves as a cofactor for Factor I in cleaving the C4B
MCP
Aka CD55
DAF
